An olefin polymer is manufactured in recent years using a metallocene-based catalyst, and used as a wax component or a lubricating oil component. In the production of an olefin polymer, in order to deactivate a catalyst after the completion of a polymerization reaction or in order to remove metal components derived from a polymerization reaction catalyst, in general, an aqueous alkaline solution such as sodium hydroxide and a polymerization reaction liquid are mixed (liquid-liquid mixture), whereby metal components are extracted in an aqueous alkaline phase. When a product is manufactured without removing the metal component in the polymerization reaction liquid, the product normally contains metal components in an amount of several tens to several hundreds wtppm. These metal components may exert adverse effects when the olefin polymer is used as a lubricating oil component.
In the Patent Document 1, in order to prevent an excessive polymerization reaction, an active proton-containing oxygen compound is added after the completion of the polymerization. Since no filtration is conducted thereafter, in Examples, aluminum or sodium remains in an amount of 1 wtppm or more.
A method is generally conducted in which a catalyst residue is absorbed by bringing a crude product obtained after polymerization into contact with a solid adsorbent (alumina, acid clay, celite, or the like), followed by filtration. However, in this method, metal components cannot be removed sufficiently.